The invention relates to sequential color imagery and, in particular, to balancing colors in a video system using sequential color imagery.
With the advent of small charge coupled devices (CCD), it is now possible to construct an extremely small video camera that can be brought into confined areas that have heretofore been found inaccessible by this type of video equipment. Typically, the camera will contain only a single black and white CCD image recorder. In order to generate a color picture, three color separated monochrome images of a traget are created and recorded during each video frame to derive information concerning the primaries of red, green and blue. An endoscope employing a small CCD equipped camera for viewing remote body cavities is disclosed by Kakinuma et al in U.S. Pat. No. 4,074,306. The Kakinuma et al instrument utilizes a color wheel to provide the necessary color separation. Red, green and blue filters are rotated past a lamp that is adapted to illuminate a target in the image plane of the camera. The color separated images are recorded in sequence by the camera and, after the signals are processed, the color images are laid down one over the other upon a Braun tube.
Beyond the disadvantages relating to sequentially laying down the color images on a Braun tube, the Kakinuma et al. system makes no provision for properly balancing the amount of color contained in each separated image so that when the images are recombined, the video picture accurately depicts the colors found in the original. As a consequence, the Kakinuma et al endoscope cannot deliver the color purity needed to make an accurate visual diagnosis of the viewed body region and the usefulness of the instrument is severely limited.